I just replaced my spark plugs in my 1999 E320 and the car runs as smooth as glass. Yet this mechanic says I need spark plug wires; is he trying to rip me off? The daignostic I had done on the car a month ago showed no need for wires.

 

the book says 100 thousand miles but that depends on various things. i wouldnt replace the wires especially if you dont have a missfire or rough idle and also if the CE lights not on then you dont have an issue. i wouldnt replace them.